A. Field of Invention PA1 B. Description of Related art
The present invention relates generally to ramp mechanisms for loading items into the load bed of trucks, and more particularly to a new and improved loading ramp mechanism for loading wheeled vehicles of various wheel base widths.
A number of loading ramp devices have been designed for use as ramps for the purpose of assisting the placement of cargo loads into the load bed of a small truck, particularly trucks commonly known as pick-up trucks. Many small trucks are not ordinarily equipped with built in loading ramps due to the compact size and low cost of the truck and the desirability of maximizing the available cargo space. Often the cargo to be loaded is quite difficult or impossible to load without the assistance of a lift or ramp. This is particularly true of motorized wheeled equipment such as lawn tractors which tend to be quite heavy while being small enough to be conveniently transported in the cargo bed of a small truck, provided loading and unloading can be performed without undue difficulty. The desired features of a loading ramp device are that it is of variable width and capable of being stored compactly as an integral part of the truck without reducing the available load bed. Known ramp devices commonly are either removable, being designed to be detached when not in use and stored in the cargo space, or built into the load bed floor, walls or both. Such known ramp devices require use of storage space within the cargo area and thereby reduce the load carrying capacity of the truck on which they are used. One means of avoiding storage of the ramp device in the cargo bed is shown in U.S. Pat. No. 4,003,483 to Fulton which discloses a tailgate capable of being pivoted into position for use as a ramp. Since the usual tailgate is less than two feet in height, the Fulton device as a ramp would not be wide enough for loading most wheeled vehicles excepting those of the smallest wheelbase width. A somewhat similar device is disclosed in U.S. Pat. No. 4,596,417 to Bennett having the same dual functionality of tailgate and ramp limiting the usefulness of the device as a ramp by reason of the width being limited to the height of the tailgate which is generally less than the width required to load wheeled equipment. All ramp devices that are of a fixed width are thereby limited in their usefulness, and are only useful as walkways. One reason for some of the known ramp design particulars is the perceived need to either replace the tailgate function of restraining loaded cargo or to load onto the lowered tailgate rather than directly into the load bed.